JP2010027263A - Battery module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery module capable of securing safety even when brought into an abnormal state. <P>SOLUTION: This battery module 60 is provided with a battery pack 30 arranged layeredly with eight unit cells, a current shut-off mechanism 40 having a connecting member arranged in one side of the battery pack 30 and for connecting a terminal of the unit cell in a maximum potential side of the battery pack 30 to a positive electrode external terminal 16, and a push piece arranged between the battery pack 30 and the connecting member, and for breaking the connecting member by movement of the push piece, to break the connection between the terminal of the unit cell in the maximum potential side of the battery pack 30 and the positive electrode external terminal 16, when the unit cells constituting the battery pack 30 are expanded when the battery is abnormal, and a resistor 50 (470 Ω, 5W) connected between the terminal in the maximum potential side of the battery pack 30 and the positive electrode external terminal 16, in parallel to the connecting member constituting the current shut-off mechanism 40. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery module, and more particularly, to a battery module including a plurality of secondary batteries arranged in a single or stacked manner.

  2. Description of the Related Art Conventionally, for example, a secondary battery used as a power source for an electric vehicle or the like is a battery module in which a large number of so-called cylindrical sealed single cells (for example, 40 to 100) are connected in series or in series and parallel. Is used.

  On the other hand, since a plurality of cylindrical sealed batteries have a low space occupancy ratio and a poor volume efficiency when a plurality of cylindrical sealed batteries are disposed, a prismatic battery using a rectangular battery container has been proposed. The rectangular battery includes a flat battery in which a flat electrode group is housed in a battery container. In addition, an iron-based container is generally used for a cylindrical sealed battery in order to reduce costs, but iron has a large specific gravity, which is a great limitation in increasing the weight efficiency of the battery. For this reason, a so-called laminated battery using a laminated film in which an aluminum foil or the like is incorporated in an inner layer as a gas barrier layer is used as a battery container has been proposed (for example, see Patent Document 1).

By the way, some cylindrical sealed cells have a weakness that is provided in the electric circuit inside the battery using the internal pressure increase due to gas generation, in case of overcharging due to failure or misuse of the charging device. Some of them incorporate a so-called current interrupting mechanism that interrupts the current before breaking up by breaking the part. In addition, a thermal fuse or PTC (Positive
There is also disclosed a technique in which a current is interrupted when a temperature rises by providing a (temperature coefficient) element (see, for example, Patent Document 2).

JP-A-60-230354 JP 2004-178994 A

  However, if a current interruption mechanism or the like is incorporated inside the unit cell, the conduction between the overcharged electrode group and the external terminal of the unit cell is interrupted when the current interruption mechanism or the like is activated. The electrode group cannot be discharged to a safe state. On the other hand, in the case of a prismatic battery or a laminated battery, it is difficult to incorporate a current interrupting mechanism or the like in each single cell because of the shape and the pressure resistance of the container. For this reason, if gas is generated in an overcharged state, the safety valve is activated or the battery case is ruptured and the gas is discharged, but the current cannot be interrupted. There is a risk. In order to solve such problems in rectangular batteries and laminated batteries, the present inventors have used a current interruption mechanism that breaks a fragile portion provided in an electric circuit of a battery module by utilizing an increase in internal pressure during overcharging. Proposed (Japanese Patent Application 2007-298952, Japanese Patent Application 2007-298976). According to this current interruption mechanism, even if the positive and negative external terminals of the battery module are short-circuited, no current flows, so that a short-circuit accident can be prevented. However, the built-in secondary battery remains in an overcharged state, and it is difficult to discharge to a safe state.

  An object of the present invention is to provide a battery module that can ensure safety even in an abnormal state.

  In order to solve the above problems, the present invention provides a battery module, a plurality of single or stacked secondary batteries, and a maximum potential or a minimum potential of the secondary battery disposed on one side of the secondary battery. Connecting a potential-side terminal to one of the positive and negative external terminals, or a connection member inserted in a connection path of the secondary battery, and the secondary battery or the stacked secondary battery And when the secondary battery expands in the event of a battery abnormality, the connection member is broken by the movement of the push block and the external terminal And a resistor connected in parallel with the connecting member constituting the current interrupting mechanism.

  In the present invention, at the normal time, a terminal on the highest potential or lowest potential side of the secondary battery arranged on one side of a plurality of secondary batteries arranged in a single or stacked manner is either one of the positive and negative external terminals. The secondary battery is connected to the positive and negative external terminals through a connection member that is connected to or inserted into the connection path of the secondary battery. For this reason, the battery module functions as a power storage system that supplies power to the outside using a secondary battery as a power source or is charged from the outside. On the other hand, when the battery is abnormal, the secondary battery expands due to the generation of internal gas, and the connecting member is broken and the electrical connection with the external terminal is interrupted by the movement of the push sesame, so the secondary battery is a battery such as an overcharged battery. Even if it falls into an abnormal state, further charging can be prevented. Moreover, since the resistor is connected in parallel with the connection member, the secondary battery constituting the battery module can be discharged to a safe state with a weak current by short-circuiting the positive and negative external terminals with a conductive wire. . Therefore, according to the present invention, safety can be ensured even in an abnormal state.

  In the present invention, the resistor has a current value of 0.1 A that flows when the positive and negative external terminals are short-circuited in a state where the connecting member constituting the current interrupting mechanism is broken and the electrical connection with the external terminal is interrupted. It is preferable that the resistance value is set so as to be as follows, and it is more preferable to have a rating that can withstand continuous short circuit energization between the positive and negative external terminals at the current value. As the secondary battery, a lithium ion battery having a laminate film as a battery container or a lithium ion battery having a square battery container may be used.

  According to the present invention, when the battery is abnormal, the secondary battery expands due to the generation of the internal gas, and the connection member is broken by the movement of the push sesame and the connection between the terminal of the secondary battery and the external terminal is interrupted. Even if the secondary battery falls into an abnormal battery state, further charging can be prevented and a resistor is connected between the secondary battery terminal and the external terminal in parallel with the connection member, so the positive and negative external terminals By short-circuiting with a conducting wire, the effect that the secondary battery which comprises a battery module can be discharged to a safe state with a weak electric current can be acquired.

  Hereinafter, an embodiment in which the present invention is applied to a battery module for a hybrid vehicle will be described with reference to the drawings.

(Constitution)
As shown in FIG. 1, a battery module (hereinafter simply referred to as a module) 60 of the present embodiment includes eight laminated batteries (hereinafter referred to as single cells) 20 using a flexible laminate film as a battery container. It has the assembled battery 30 connected. The assembled battery 30 and the entire current interrupting mechanism, resistor, and the like described later are incorporated in an aluminum alloy frame (indicated by a chain line in FIG. 1) to constitute a module 60.

<Battery assembly>
The eight unit cells 20 are arranged so that the positive and negative electrode terminals are alternately arranged, and each unit cell 20 has a flat portion on two opposing surfaces. Adjacent unit cells 20 are arranged so that the flat portions thereof are opposed to each other, and the adjacent unit cells 20 are bonded to each other with a double-sided tape. Therefore, the assembled battery 30 is provided with the unit cells 20 in a stacked state. The terminals of the adjacent unit cells 20 are joined by resistance welding using a nickel plate, and the eight unit cells 20 are connected in series. The cell unit 20a on the highest potential side disposed on one side (right side in FIG. 1) of the eight unit cells 20 has a battery capacity set to be about 5% smaller than the other seven unit cells 20. . Among the cells constituting the assembled battery 30, the negative electrode terminal of the cell 20 on the lowest potential side disposed on the side opposite to the cell 20 a is connected to the negative external terminal 15 of the module 60.

  As shown in FIG. 2, the unit cell 20 constituting the assembled battery 30 has two rectangular laminate films (hereinafter simply referred to as films) 1, 1 ′ used for an exterior body (battery container). Yes. The films 1 and 1 ′ are laminated with a polypropylene (PP) film, an aluminum foil, and a polyethylene terephthalate (PET) film. An electrode group 4 is enclosed between the films 1 and 1 '. The film 1 ′ located on one side of the electrode group 4 is a flat film formed in a flat shape, and the film 1 located on the other side is a cup-shaped film having a substantially central portion formed into a convex shape. Two positive electrode terminals 2 and two negative electrode terminals 3 are provided on the two opposite sides of the film 1 ′ so as to protrude outward in opposite directions. The four sides of the peripheral portions of the films 1 and 1 ′ are sealed with the welded portion 10 by heat welding, and the unit cell 20 has a sealed structure. Each positive electrode terminal 2 and each negative electrode terminal 3 are sandwiched between the welding portions 10 via a sealing material 11.

  In the electrode group 4, 19 positive plates and 20 negative plates are alternately stacked. The positive electrode plate is inserted into a separator formed into a bag shape by heat welding. For the separator, for example, a polyethylene porous film having a thickness of 25 μm is used. The positive electrode plate and the negative electrode plate are overlapped so that the positive electrode terminal 2 and the negative electrode terminal 3 are led out in directions opposite to each other. The positive electrode terminal 2 and the negative electrode terminal 3 are arranged so as to be symmetric with respect to the horizontal center line between two opposing sides of the films 1, 1 ′. The two positive terminals 2 and the two negative terminals 3 pass through the centers of the positive strap 6 and the negative strap 8 (the centers of the two opposing sides) and are formed at symmetrical positions with respect to the vertical center line. That is, the positive electrode terminal 2 and the negative electrode terminal 3 are led out from the two opposite sides of the film container via the positive electrode strap 6 and the negative electrode strap 8, respectively.

  The positive electrode strap 6 formed integrally with the positive electrode terminal 2 uses an aluminum alloy A3003-H12 (Japanese Industrial Standard), and the portion of the positive electrode terminal 2 that is not in contact with the electrolyte (the portion exposed to the outside of the battery) Only) has a nickel plate clad on one side. On the other hand, a copper plate C1020-1 / 2H (Japanese Industrial Standard) is used for the negative electrode strap 8 formed integrally with the negative electrode terminal 3, and a nickel plate is formed on both surfaces only at the portion of the negative electrode terminal 3 exposed to the outside of the battery. Is clad. The positive strap 6 and the negative strap 8 are ultrasonically welded to the active material uncoated portion 7 of the positive current collector and the active material uncoated portion 9 of the negative current collector, respectively. In the positive electrode terminal 2 and the negative electrode terminal 3, a circular reference hole 5 for alignment is formed at a substantially central portion in the derived width direction so as to be parallel to the horizontal center line. The positive electrode terminal 2 and the negative electrode terminal 3 are respectively formed with a rectangular cutout portion 2 ′ and a cutout portion 3 ′ on one side in the lead-out width direction.

  At the time of assembling the unit cell 20, the electrode group 4 is placed at the substantially central portion of the film 1, the film 1 'is placed, and the four-side welded portion 10 is thermally welded. At this time, after a predetermined amount of electrolytic solution was injected from the mating surfaces of the films 1 and 1 ′ which had not been thermally welded, using a syringe, this portion was again thermally welded and sealed. Battery 20 is produced. By inserting a pin (not shown) into the reference hole 5 and positioning the positive electrode terminal 2 and the negative electrode terminal 3 during a series of assembly operations, the required dimensional accuracy can be obtained. The rated capacity of the unit cell 20 is 10 Ah. The unit cell 20a is produced in the same manner as the unit cell 20 except that the electrode group 4 is composed of 18 positive plates and 19 negative plates, and has a rated capacity of 9.5 Ah.

  At the time of producing the positive electrode plate constituting the electrode group 4, lithium manganate having an average particle diameter of 10 μm, carbon powder having an average particle diameter of 3 μm, and polyvinylidene fluoride as a binder (trade name: KF # 120, Kureha Chemical Industry ( The slurry is produced by mixing with the dispersion solvent N-methyl-2-pyrrolidone. This slurry is applied to both surfaces of a 20 μm thick aluminum foil (positive electrode current collector), dried, pressed and integrated. Thereafter, a strip-shaped positive electrode plate is produced by cutting to a predetermined width.

  On the other hand, when producing the negative electrode plate, carbon particles having an average particle diameter of 20 μm and polyvinylidene fluoride (trade name: KF # 120, manufactured by Kureha Chemical Industry Co., Ltd.) as a binder are dispersed solvent N-methyl-2. -A slurry is made by mixing with pyrrolidone. This slurry is applied on both sides of a 10 μm thick copper foil (negative electrode current collector), dried, pressed and integrated. Thereafter, it is cut into a predetermined width to produce a negative electrode plate.

<Current interruption mechanism>
As shown in FIG. 1, the unit cell 20 a has a disk-like shape that receives an expansion force when one of the unit cells 20, 20 a expands at the approximate center of the plane portion opposite to the adjacent unit cell 20. The pressure receiving plate 13 is fixed with a double-sided adhesive tape. The pressure receiving plate 13 is made of a non-conductive and rigid material such as phenol resin. On the opposite side of the pressure receiving plate 13 from the unit cell 20a, a push block 14 for interrupting current when the unit cells 20 and 20a expand is disposed. The push sesame 14 is made of a non-conductive material. The push sesame 14 has a disk-shaped base portion 14a on the pressure receiving plate 13 side. The base portion 14 a is formed in a planar shape in which one surface on the pressure receiving plate 13 side can come into contact with the pressure receiving plate 13, and the diameter of the base portion 14 a is set smaller than that of the pressure receiving plate 13. On the surface (other surface) opposite to the pressure receiving plate 13 of the base portion 14a, two substantially cylindrical protrusions 14b project from the vicinity of the center of the base portion 14a. The protruding lengths of the two protruding portions 14b are the same. For this reason, the push sesame 14 has a substantially π-shaped cross section.

  A disc-shaped conductive plate 17 made of an aluminum alloy is disposed on the side opposite to the pressure receiving plate 13 of the push sesame 14. That is, the conductive plate 17 is disposed so as to face the unit cell 20a. The conductive plate 17 is formed with two circular through holes 17a through which the protrusions 14b can penetrate at positions corresponding to the protrusions 14b of the push sesame 14. In other words, the conductive plate 17 has the same number of through holes 17a as the protrusions 14b. A conductive plate 18 made of an aluminum alloy and functioning as a diaphragm is disposed on the opposite side of the conductive plate 17 from the push block 14. The center of the conductive plate 18 is flat and protrudes toward the conductive plate 17, and covers the through hole 17 a formed in the conductive plate 17. The centers of the conductive plate 17 and the conductive plate 18 are joined at the joint 21 by friction stir welding. For this reason, the protrusion 14 b of the push sesame 14 passes through the through hole 17 a formed in the conductive plate 17, so that the tip of the protrusion 14 b contacts the conductive plate 18. The outer peripheral portion of the conductive plate 18 is separated from the outer peripheral portion of the conductive plate 17, and an annular insulating member 19 is interposed between the conductive plates 17 and 18. An insulating member 19 ′ is disposed on the outer peripheral portion of the conductive plate 18 opposite to the conductive plate 17 so as to correspond to the insulating member 19.

  The conductive plate 17 is connected to the positive terminal of the unit cell 20 a, and the conductive plate 18 is connected to the positive external terminal 16 of the module 60. Therefore, the conductive plates 17 and 18 and the joint portion 21 (strictly, further including the insulating members 19 and 19 ′) constitute a connecting member for connecting the positive terminal of the unit cell 20a to the positive external terminal 16. Yes. The current interrupting mechanism 40 is composed of this connecting member and the above-described pushing sesame 14, and when the single cells 20 and 20 a constituting the assembled battery 30 expand when the battery is abnormal, the connecting member is moved by the pushing sesame 14. It has a function of breaking the (bonding of the conductive plates 17 and 18 by the bonding portion 21) to cut off the connection between the positive electrode terminal of the unit cell 20a and the positive electrode external terminal 16 of the module 60. In addition, the resistance value of the connection member 40 is very small, and the actual measurement value in this embodiment is 0.34 mΩ.

<Resistors>
Moreover, in the module 60 of this embodiment, as shown in FIG. 3, it is parallel to the connection member which comprises the electric current interruption mechanism 40, ie, between the positive electrode terminal of the cell 20a, and the positive electrode external terminal 16 of the module 60. A resistor 50 having a resistance value of 470Ω and a rating of 5 W is inserted (connected) (between A and B in FIG. 1).

(Operation etc.)
Next, operation | movement of the module 60 of this embodiment, etc. are demonstrated.

<Normal time>
In the present embodiment, the conductive plate 17 connected to the positive terminal of the unit cell 20 a and the conductive plate 18 connected to the positive external terminal 16 are connected via the joint portion 21. That is, the highest potential side of the assembled battery 30 is connected to the positive external terminal 16 via the connection member. For this reason, the module 60 functions as a power storage system in which electric power is supplied to the outside using the assembled battery 30 as a power source or the electric power is charged from the outside. In addition, since the single cells 20 and 20a of this embodiment are lithium ion batteries, when the module 60 is made to function (charge / discharge), the charge state (SOH) of each single cell is controlled to be substantially uniform. A control circuit (not shown) is connected.

  As described above, the resistance value of the connecting member of the current interrupt mechanism 40 is extremely low (0.34 mΩ), and the resistance value of the resistor 50 is 470Ω (rated 5 W). In the example, when the module 60 is mounted on a vehicle and functions normally as a power storage system), the charging / discharging current of the assembled battery 30 almost flows through the current interrupting mechanism 40, and the resistor 50 has about 1 of the total current. Only a weak current of 1,400,000 flows. Therefore, the energy loss due to the heat generated by the resistor 50 can be ignored. In the normal state, the push sesame 14 maintains its position (does not move).

<When battery is abnormal>
In order to test the battery abnormal state in a simulated manner, a simulation apparatus 100 corresponding to the vehicle side was connected to the module 60 as shown in FIG. The simulation apparatus 100 includes a main switch 91 having one end connected to the positive external terminal 16 and the other end connected to the changeover switch 92, and a variable resistor that has one end connected to the negative external terminal 15 and the other end connected to the changeover switch 92. And a charging device 94 having one end connected to the negative external terminal 15 and the other end connected to the changeover switch 92. The variable resistor 93 imitates the load of the vehicle, and the charging device 94 can output a maximum of 40V and 2A. The variable resistor 93 and the charging device 94 can be switched by a changeover switch 92 simulating a mechanism for controlling the state of charge.

  The main switch 91 of the simulation apparatus 100 was turned on, and the changeover switch 92 was switched to the charging device 94 side to enter a continuous charge state. Approximately 16 hours later, gas generation occurred inside the battery, and the current interrupt mechanism 40 was activated to interrupt the current.

  That is, the unit cells 20 and 20a are overcharged, the electrolyte is decomposed inside the unit cell, gas is generated, and the film (battery container) of the exterior body expands. As a result, the pressure receiving plate 13 fixed to the unit cell 20a moves the pressing sesame 14 to the connecting member side (the right side in FIG. 1), and the tip end portion of the projecting portion 14b presses the center of the conductive plate 18 to cause the conductive plate 17 to move. , 18 are broken, and the diaphragm-like conductive plate 18 is inverted. Once the conductive plate 18 is reversed, it does not return to its original state, and the state where the conductive plate 18 is blocked from charging from the charging device 94 side is maintained.

  Thereafter, the charging current from the charging device 94 flows only through the resistor 50. However, since the resistance value of the resistor 50 is extremely large as described above, the flowing current becomes weak. The actually measured value in the module 60 of the present embodiment was about 8 mA. At this time, if there is no abnormality in the above-described control circuit, the voltage between both terminals of the resistor 50 rapidly rises from about 0 V to about 3.8 V, so that the abnormality is detected and the main switch 91 is turned off. Treatment becomes possible. Since such a control mechanism is omitted in the simulation apparatus 100, the charging current continued to flow. However, since the current was weak, the cells 20 and 20a did not burst or ignite even after 240 hours.

  When the current cut-off mechanism 40 is activated, the module 60 is removed from the vehicle, and the positive external terminal 16 and the negative external terminal 15 of the module 60 are short-circuited using a conducting wire, and assembled with a weak current via the resistor 50. The battery 30 can be discharged until it is in a safe state. In this embodiment, since the 470Ω resistor 50 is used, the initial current at the time of short circuit is about 0.08A. Further, since a resistor having a rating of 5 W was used as the resistor 50, it was able to withstand even a complete discharge. That is, since the resistance value of the resistor 50 is selected so that the current flowing when the two pole external terminals of the module 60 are short-circuited is 0.1 A or less, the load power of the resistor 50 is suppressed to about 5 W or less. I can. Therefore, a small resistor is sufficient for the resistor 50. On the other hand, if the resistance value is reduced, it can be discharged in a shorter time, but the load power of the resistor increases and a resistor with a large rating is required. This will increase costs. Even if the current is about 0.1 A, the battery in an overcharged state can be almost completely discharged if it is left short for about 10 days.

  By the way, since it is unavoidable that the battery capacity of the single battery 20 varies to some extent, the battery capacity of the single battery that can come into contact with the push sesame 14 out of the single battery built in the module 60 is accidentally large. For example, gas generation may be delayed in a unit cell having a large battery capacity even in an overcharged state. For this reason, even if any one of the unit cells 20 expands, the pressing force is not sufficiently transmitted to the pressing sesame 14, and before the current is cut off by the pressing sesame 14, another unit cell having a relatively small battery capacity is obtained. There is a possibility of explosion due to ignition or internal pressure increase. In the module 60, the battery capacity of the unit cell 20 a that can come into contact with the push sesame 14 is set to be 5% smaller than the other unit cells 20. For this reason, in the overcharged state or the like, the increase in the internal pressure of the unit cell 20a is faster than that of the other unit cells 20. Therefore, the charging current can be surely interrupted by transmitting the pressing force due to the expansion of the unit cell 20a to the push pad 14. it can. Further, in the module 60, since the electrode group 4 is formed in a stacked type in which the positive electrode plate and the negative electrode plate are superposed, the unit number of the positive electrode plate and the negative electrode plate is reduced to reduce the unit capacity of the single battery 20 smaller than that of the single battery 20. The battery 20a can be easily manufactured.

  In the present embodiment, the current interrupting mechanism 40 having the π-shaped pusher 14 and the conductive plate 18 functioning as a diaphragm is illustrated, but the present invention is not limited to this. For example, as shown in FIGS. 4 and 5, a rectangular lead plate 27 made of an aluminum alloy may be disposed on the side opposite to the pressure receiving plate 13 of the block-like or columnar push sesame 24. Triangular notches are formed at approximately the center in the longitudinal direction of the lead plate 27 by punching with a press on both sides in the width direction orthogonal to the longitudinal direction. That is, the lead plate 27 has a narrowed portion 28 at a substantially central portion. In the narrow portion 28, the central portion 33 showing the minimum width constitutes a weak portion of the lead plate 27.

  A support member 29 that supports the lead plate 27 is disposed on the opposite side of the lead plate 27 from the push block 24. The support member 29 is formed in a circular shape, and a non-conductive material such as a phenol resin is used. On one surface side of the support member 29, the lead plate 27 is supported by a portion below the center portion 33. Therefore, the push sesame 24 and the support member 29 are positioned on the opposite sides with respect to the central portion 33 of the lead plate 27. The other side of the support member 29 and the portion above the central portion 33 of the lead plate 27 are supported by a frame not shown. The support member 29 has a protrusion 32 at the upper end on the lead plate 27 side. The protrusion 32 is formed integrally with the support member 29. The protrusion 32 has a tongue shape and is disposed at a position corresponding to the central portion 33 of the lead plate 27. In other words, the protruding portion 32 is disposed so as to contact the narrow portion 28 including the central portion 33.

  One end of the lead plate 27 is connected to the positive terminal of the unit cell 20 a with the central portion 33 interposed therebetween, and the other end is connected to the positive external terminal 16. For this reason, the positive electrode external terminal 16 and the positive electrode terminal of the unit cell 20 a are connected via the lead plate 27 including the central portion 33. In this embodiment, the lead plate 27 constitutes a connection member, but strictly speaking, the connection member includes a support member 29 and a protrusion 32. The current interruption mechanism 40 ′ is composed of this connecting member and the above-described push sesame 24. In addition, in parallel with the connection member constituting the current interruption mechanism 40 ′, that is, between the positive terminal of the unit cell 20a and the positive external terminal 16 of the module 60 ′ (between A and B in FIG. 4), a resistance A resistor 50 having a value of 470Ω and a rating of 5 W is inserted.

  When the module 60 ′ is overcharged due to a device failure or the like, the battery becomes abnormal, gas is generated inside the battery due to evaporation or decomposition of the electrolyte, and the internal pressure rises. When one of the cells 20 and 20a expands due to an increase in internal pressure, the cell 20 arranged on the opposite side of the cell 20 from the cell 20a is supported by the frame of the module 60 ′, which is not shown. The pressure receiving plate 13 is pressed toward the pressing sesame 24 and comes into contact with the pressing sesame 24. For this reason, the pushing sesame 24 is pressed and moved toward the lead plate 27, and the lead plate 27 is pushed by the pushing sesame 24. As a result, the central portion 33 of the lead plate 27 is broken, so that the connection between the unit cell 20a and the positive electrode external terminal 16 is cut off, and the positive electrode side conductive path of the module 60 'is cut off.

  Further, the support member 29 has a tongue-like protrusion 32 at the upper end on the lead plate 27 side, and the protrusion 32 is disposed so as to contact the narrow portion 28 including the central portion 33 of the lead plate 27. For this reason, after the central portion 33 is broken, the upper broken end portion of the broken central portion 33 goes around the protruding portion 32 to the opposite side to the lower broken end portion. Thereby, the fracture | rupture end parts of the fracture | ruptured center part 33 can be spaced apart by the projection part 32. FIG. Even if the internal pressure is reduced due to damage to the film of the battery container or lowering of the battery temperature, the broken lead plate 27 does not return to its original state due to elasticity. It can be prevented from flowing.

  Further, when the current interrupting mechanism 40 ′ is activated, the module 60 ′ is removed from the vehicle, and the positive electrode external terminal 16 and the negative electrode external terminal 15 of the module 60 are short-circuited using a lead wire, thereby connecting the resistor 50 through the resistor 50. The battery pack 30 can be discharged with a weak current until it is in a safe state.

  Moreover, in this embodiment, although the laminated battery was illustrated as the single battery, this invention is not restrict | limited to this. For example, a lithium ion battery having a square container made of metal (for example, stainless steel or nickel-plated iron) can be used as the single battery constituting the assembled battery 30. In such a lithium ion battery, in addition to the electrode group in which the positive and negative electrode plates are stacked via the separator, a flat electrode group in which the positive and negative electrode plates are wound through the separator may be used. The present inventors have grasped the fact that such a prismatic battery generally expands by about 5 mm when the internal pressure rises by 1 atm (101.325 kPa), and when a plurality of single cells are juxtaposed (stacked arrangement) It is considered that the current interruption mechanism functions sufficiently.

  Furthermore, in this embodiment, although the example which adheres the pressure receiving plate 13 to the plane part by the side of the pushing sesame 14 of the cell 20a was shown, this invention is not limited to this, The plane part of the cell 20a is You may make it contact | abut to the pushing sesame 14 directly. By adopting a structure that pushes the push sesame 14 through the pressure receiving plate 13 having a larger area and rigidity than the push sesame 14, the expansion force when any of the single cells 20, 20 a expands is effectively applied to the push sesame 14. Since it is transmitted, current interruption can be reliably performed. Further, in the present embodiment, the non-conductive material is exemplified for the pressure-receiving plate 13 and the pressing sesame 14. However, the present invention is not limited to this. For example, the films 1 and 1 ′ may be non-conductive. For example, a conductive material may be used for the pressure receiving plate 13 and the pressing sesame 14.

  In the present embodiment, the conductive plate 18 is connected to the positive electrode external terminal 16 of the module 60, and the conductive plate 17 is connected to the positive electrode terminal of the unit cell 20a to configure the positive electrode side conductive path. The present invention is not limited to this. For example, the conductive plate 18 may be connected to the positive terminal of the unit cell 20 a and the conductive plate 17 may be connected to the positive external terminal 16. Of course, it is also possible to provide a mechanism for cutting off the current using the push sesame 14 on the negative electrode side. In this case, for example, the conductive plate 18 is connected to the negative electrode external terminal 15 of the module 60, and the conductive plate 17 is connected to the negative electrode terminal of the unit cell 20 located on the outermost side opposite to the unit cell 20a. can do. Still further, the current interruption mechanism 40 may be inserted into the connection path of the unit cells 20, and even in such an embodiment, a part of the unit cells 20 arranged in a stacked manner when the battery is abnormal causes the push sesame 14 and 24 to be pushed. The electrical connection with the external terminal can be interrupted by pressing.

  Furthermore, in this embodiment, in order to ensure the certainty of the electric current interruption mechanism 40, the example which made the battery capacity of the cell 20a 5% smaller than the cell 20 was shown, but this invention is limited to this. Instead, it is preferable to make it small in the range of 3 to 9%. However, if it is unavoidable due to manufacturing reasons or the like, even if the battery capacity of the unit cells constituting the assembled battery 30 is the same, the reliability of the current interrupting mechanism 40 is not significantly impaired due to a comparative problem. .

  Furthermore, in the present embodiment, the friction stir welding is illustrated as the joining of the conductive plates 17 and 18, but the conductive plates 17 and 18 may be joined by resistance welding. Moreover, although the example which made the electrically conductive plates 17 and 18 the product made from an aluminum alloy was shown, if it is a material which has electroconductivity, it will not restrict | limit in particular. Considering weight reduction of the entire module, it is preferable to use an aluminum alloy. Furthermore, in this embodiment, although the example which formed the protrusion part 14b of the push sesame 14 was shown, it is also possible to set it as three, four, etc., for example. Of course, the shape of the protrusion 14b is not limited to a cylindrical shape. In this case, it is necessary to form the same number of through holes 17a as the protrusions 14b in the conductive plate 17 so as to correspond to the protrusions 14b (including the shape). In the present embodiment, the pressure receiving plate 13, the base 14 a of the pressing sesame 14, and the conductive plates 17 and 18 are shown as circular shapes, but the present invention is not limited to these shapes, for example, Alternatively, a rectangular shape or the like may be used.

  Further, in the present embodiment, an example in which eight unit cells 20 are connected in series has been shown, but the present invention is not limited to the number of unit cells, and as a connection form such as series-parallel connection other than series connection. Also good. And in this embodiment, although the example of the secondary battery module comprised by the some single battery was demonstrated, this invention is not restrict | limited to this, The module 60 is one single battery (single battery). It is also applicable when configured with

  Since the present invention provides a battery module that can ensure safety even in an abnormal state, it contributes to the manufacture and sale of battery modules, and thus has industrial applicability.

It is sectional drawing which shows typically the battery module of embodiment which can apply this invention. It is the top view and side sectional view of the state except the convex film of the cell which constitutes the battery module of an embodiment. It is a circuit diagram when the battery module of embodiment and the simulation apparatus are connected. It is sectional drawing which shows typically the battery module of other embodiment which can apply this invention. It is explanatory drawing which shows typically the narrow part of the lead plate integrated in the battery module of other embodiment.

Explanation of symbols

14, 24 Push sesame 15 Negative external terminal 16 Positive external terminal 17, 18 Conductive plate (part of connecting member)
21 Junction (part of connecting member)
27 Lead plate (part of connecting member)
30 battery pack (secondary battery)
40, 40 'Current interruption mechanism 50 Resistor 60, 60' Battery module

Claims (5)

A plurality of secondary batteries arranged in a single or stacked manner;
The terminal of the secondary battery arranged on one side of the secondary battery is connected to one of the positive and negative external terminals or inserted into the connection path of the secondary battery. A connecting member and a push block disposed between the connecting member and a part of the secondary battery or the stacked secondary battery and the connecting member, and the secondary battery expands when the battery is abnormal Sometimes, a current interruption mechanism for breaking the connection member by the movement of the push sesame and breaking the electrical connection with the external terminal,
A resistor connected in parallel with a connecting member constituting the current interrupting mechanism;
Battery module with   The resistor has a current value of 0.1 A flowing when the positive and negative external terminals are short-circuited in a state in which the connection member constituting the current interrupting mechanism is broken and the electrical connection with the external terminal is interrupted. The battery module according to claim 1, wherein the resistance value is set to be as follows.   The battery module according to claim 2, wherein the resistor has a rating capable of withstanding continuous short circuit energization between the positive and negative external terminals at the current value.   The battery module according to claim 1, wherein the secondary battery is a lithium ion battery using a laminate film as a battery container.   The battery module according to claim 1, wherein the secondary battery is a lithium ion battery having a rectangular battery container.

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